Pseudolipomatosis in Hysteroscopically-Assessed Tissue (PHAT): Pathologic Features and Frequency
ZM Unger, JL Gonzalez, AR Schned. Dartmouth-Hitchcock Medical Center, Lebanon, NH
Background: Pseudolipomatosis is an artifactual microscopic change in tissues that resembles fatty infiltration, most frequently seen in the GI tract. In this condition, fat-like spaces represent air or gas bubbles that enter the mucosa through microscopic ruptures secondary to gaseous insufflation. We recently encountered two cases exhibiting a similar appearance in tissues removed during hysteroscopic procedures in the gynecologic tract, a finding not previously described. We therefore performed a retrospective review to assess the frequency of pseudolipomatosis in hysteroscopically-assessed tissues (PHAT) and to define the morphologic features in a large series.
Design: We identified 300 consecutive hysteroscopic procedures performed at our institution from August 2006 to January 2008 using Current Procedural Terminology codes. Patient medical records were reviewed to collect pertinent clinical data. Slides from all cases were retrieved and systematically reviewed. All cases with features suggestive of PHAT were identified on an initial review. A subsequent consensus conference established the cases identified as PHAT.
Results: A total of 28 cases of PHAT, representing 9.3% of hysteroscopied patients, were identified. PHAT was found in 9 endometrial curettings or biopsy tissues, 8 endometrial or endocervical polyps, 8 uterine fibroids, 2 fallopian tubes, and 1 endocervical biopsy. Among the 28 cases, glycine was used as distention medium in 82%, dextran 70 in 3.5%, and saline in 3.5% (11% were not recorded). The type of distention media used and length of hysteroscopic procedure did not differ significantly between cases with and without PHAT. PHAT vacuoles varied in distribution from multiple crowded clusters to sparsely scattered and solitary. In several cases, vacuoles were found in vascular channels. Vacuoles were round or ovoid, unilocular, and generally uniform in size. Immunohistochemical staining for adipocyte and endothelial markers (S-100 and CD34 respectively), were completely negative.
Conclusions: We hypothesize that PHAT is dervied from the air that is almost invariably introduced into the uterus during media insufflation for hysteroscopy, creating a bubble under pressure. The air enters tissues either through lining microruptures or during the biopsy procedure. The type of distention medium and length of procedure do not appear to be independent predisposing factors. PHAT is a relatively common, easily overlooked finding in hysteroscopically-derived pathology specimens that may be mis-diagnosed when prominent.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 168, Wednesday Afternoon